1. Field of the Invention
This invention relates to fluid compressors and is particularly concerned with multiple stage fluid compressors.
2. Description of the Prior Art
Our co-pending U.S. patent application Ser. No. 430660 discloses several embodiments of a multiple stage fluid compressor in which each compression stage is driven by a pneumatically operated drive piston. Each drive piston is controlled by control means comprising at least one inlet valve and at least one outlet valve and drive and sequencing means comprising either individual phase controlled electric solenoids or a motor such as an electric motor driving sequencing means in the form of rotating or cam operated valves through a toothed timing belt.
Such devices therefore require a compressed air power supply and another, e.g. electric, power supply which complicates installation, and the use of valves and the solenoids or electric motor complicates the design and increases its bulk and consequently its weight.